From the future pregnancies point of view you may want to find out about IVF with PGD, which is where they test few-day-old embryos, and only put the ones that don't have the dodgy gene back in to Mum.
Test development may be long and expensive for a rare disease (for my dodgy gene it was several years) - but it may also be simple, it really depends on the gene.
Best wishes to you and your family
hugs
Kate